Dual Use RFID/EAS Device

ABSTRACT

A radio frequency identification (RFID) device has multiple modes of operation. One of the modes of operation is an electronic article surveillance (EAS) mode, which is used to allow use of the RFID device as an EAS device. Another mode of operation is an RFID mode, which allows normal function of the RFID device in RFID communications. The EAS mode has greater sensitivity than the RFID mode, requires less power than the RFID mode to operate the device, and requires less current and/or voltage for operation. The EAS mode may achieve these different characteristics by one or more of: switching off some digital blocks in the circuitry of the RFID device; reducing power storage required to respond to incoming signals; reducing the length of response to incoming signals; reducing modulation required for a response; changing chip input impedance; and having multiple chip ports with different impedances.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority from U.S. Provisionalapplication Ser. No. 11/949,112 filed Dec. 3, 2007, which isincorporated by herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is in the field of devices and methods for radio frequencyidentification (RFID) and electronic article surveillance (EAS).

2. Description of the Related Art

Radio frequency identification (RFID) tags and labels (collectivelyreferred to herein as “devices”) are widely used to associate an objectwith an identification code. RFID devices generally have a combinationof antennas and analog and/or digital electronics, which may include forexample communications electronics, data memory, and control logic. Forexample, RFID tags are used in conjunction with security locks in cars,for access control to buildings, and for tracking inventory and parcels.

As noted above, RFID devices are generally categorized as labels ortags. RFID labels are RFID devices that are adhesively or otherwise havea surface attached directly to objects. RFID tags, in contrast, aresecured to objects by other means, for example by use of a plasticfastener, string or other fastening means.

RFID devices include active tags and labels, which include a powersource, and passive tags and labels, which do not. In the case ofpassive devices, in order to retrieve the information from the chip, a“base station” or “reader” sends an excitation signal to the RFID tag orlabel. The excitation signal energizes the tag or label, and the RFIDcircuitry transmits the stored information back to the reader. The RFIDreader receives and decodes the information from the RFID tag. Ingeneral, RFID tags can retain and transmit enough information touniquely identify individuals, packages, inventory and the like. RFIDtags and labels also can be characterized as to those to whichinformation is written only once (although the information may be readrepeatedly), and those to which information may be written during use.For example, RFID tags may store environmental data (that may bedetected by an associated sensor), logistical histories, state data,etc.

As the name implies, electronic article surveillance (EAS) is concernedwith the embedding or attaching of a security label or tag to a retailitem to deter shoplifting. Conventional EAS devices or tags include aresonator that, when activated, causes an alarm to sound when the EAStag is brought within operative proximity of detection apparatus (whichis typically located at the exit of a store). However, if the EAS deviceis active, a similar signal will also be produced each time that acustomer either properly removes purchased goods from the store orenters another store with similar detection apparatus. Generally, EAStags are inexpensive and disposable items that are not removed frommerchandise during check out (which is generally true for RFID tags aswell). For these reasons, a variety of different techniques have beendeveloped to deactivate EAS tags, typically by a clerk during check outusing deactivation apparatus that needs no physical contact with thetag.

Various types of EAS devices and deactivation systems make use ofspecially configured tags or labels in connection with an apparatus forpositively deactivating such tags or labels. A first example is the EAStag described in U.S. Pat. No. 4,498,076 to Lichtblau. The Lichtblau tagis provided with a resonant circuit having a capacitor portion with anindentation that permits the resonant circuit to be deactivatedaccording to methodology as described in U.S. Pat. No. 4,728,938 toKaltner, for example. The Lichtblau EAS tag is readily deactivated atthe point of sale by subjecting the tag or label to a relativelyhigh-powered signal which, because of the mechanical indentation, issufficient to cause a short circuit within the tag or label fordeactivation.

Another type of EAS tag, sometimes called a magnetomechanical EAS tag,uses the technology disclosed in U.S. Pat. No. 3,765,007 to Elder.Magnetomechanical tags include an active element and a bias element.When magnetized, the bias element applies a bias magnetic field to theactive element which causes the active element to be mechanicallyresonant at a predetermined frequency upon exposure to an interrogationsignal which alternates at the predetermined frequency. This tagrequires a relatively high magnetic field level for activation anddeactivation. Activation and deactivation is accomplished by exciting acoil wound around a magnetic core.

Some effort has been made to combine an RFID device and an EAS devicewithin a single device. U.S. Pat. No. 7,109,867 to Forster describes adevice that includes both an RFID device and an EAS device. U.S. Pat.No. 7,002,475 to Brady describes an RFID tag that includes a non-linearmagnetic material in its antennas, allowing it to function also as anEAS device. Both of these combinations involve additional structuralelements to perform the two functions in the same device.

From the forgoing it will be appreciated that improvements are possiblefor RFID devices.

SUMMARY OF THE INVENTION

According to an aspect of the invention, an RFID device has a relativelylow sensitivity RFID mode for communicating with RFID readers/detectors,and a relatively high sensitivity EAS mode for communicating with EASreaders/detectors.

According to another aspect of the invention, an RFID device alsofunctions as an EAS device, by employing an EAS mode with differentcharacteristics than for normal operation.

According to yet another aspect of the invention, a UHF RFID device alsofunctions as an EAS device, without any particular structure used in theEAS device function.

According to still another aspect of the invention, a radio frequencyidentification (RFID) device includes: an antenna; and a chipoperatively coupled to the antenna. The chip includes circuitry toselective operate the RFID device two modes: a relatively lowsensitivity RFID mode used for communicating with RFIDreaders/detectors; and a relatively high sensitivity electronic articlesurveillance (EAS) mode for communicating as EAS readers/detectors.

According to a further aspect of the invention, a method of utilizing anRFID device for use as an electronic article surveillance (EAS) device,includes the steps of: entering an improved sensitivity mode ofoperation that improves sensitivity over that of a normal mode ofoperation that is used for RFID communication; and while in the improvedsensitivity mode, communicating with an EAS reader/detector.

According to a still further aspect of the invention, a radio frequencyidentification (RFID) tag includes: a chip; and an antenna operativelycoupled to the chip. The chip including circuitry for operation betweena first mode and a second mode. Each of the first and second modesoperate at a different sensitivity.

According to another aspect of the invention, a radio frequencyidentification (RFID) tag, includes a chip; and an antenna operativelycoupled to the chip. The chip includes circuitry for operating at anormal mode and at least a second mode, and wherein the chip selectivelyoperates between the normal mode and the second mode. The chipdeactivates one of the normal mode and second mode on receipt of asignal.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the annexed drawings, which are not necessarily to scale:

FIG. 1 is a diagram of a radio frequency identification (RFID) device inaccordance with an embodiment of the present invention;

FIG. 2 is a diagram of the RFID of FIG. 1 in communication with an RFIDreader/detector;

FIG. 3 is a diagram of the RFID of FIG. 1 in communication with an RFIDreader/detector;

FIG. 4 is a diagram of an RFID device in accordance with anotherembodiment of the present invention;

FIG. 5 is a diagram of part of an RFID device in accordance with stillanother embodiment of the present invention;

FIG. 6 is a diagram of an RFID device in accordance with a furtherembodiment of the present invention; and

FIG. 7 is a diagram of part of an RFID device in accordance with a stillfurther embodiment of the present invention.

DETAILED DESCRIPTION

A radio frequency identification (RFID) device has multiple modes ofoperation. One of the modes of operation is an electronic articlesurveillance (EAS) mode, which is used to allow the RFID device tofunction better as an EAS device. Another mode of operation is an RFIDmode, which allows normal function of the RFID device in RFIDcommunications. The EAS mode has greater sensitivity than the RFID mode,requires less power than the RFID mode to operate the device, andrequires less current and/or voltage for operation. The EAS mode mayachieve these different characteristics by one or more of the following:switching off unnecessary digital blocks in the circuitry of a chip orother electronics of the RFID device; reducing power storage required torespond to incoming signals; reducing the length of response to incomingsignals; reducing modulation required for a response; changing chipinput impedance; and having multiple chip ports with differentimpedances.

The RFID device may be a device configured to interact with UHF (ultrahigh frequency) signals, for example in the range of 300 MHz to 3 GHz.The antenna gain and efficiency for a given size are inversely related.As an example, at 600 MHz and 300 MHz, for a given distance thepropagation loss at 300 MHz is 6 dB lower than at 600 MHz. If an antennasize of 250 mm is available, there can be a half wave dipole at 600 MHz,with no folding. At 300 MHz there will have to be folding or otherarrangement of the elements of the antenna to fit into the space, whichtends to reduce efficiency, gain and/or bandwidth. There are trade-offsinvolving size and frequency regarding other characteristics orfeatures, such as adsorption loss and read infrastructure. The shiftingbetween modes may be done automatically by the device based upon thecharacteristics of incoming signals to the device. Alternatively acontrol signal or control signals may be sent to the RFID device tospecifically cause the RFID device to shift between modes. The modes maybe alternatively activatable. Alternatively it may be possible for bothmodes to be active at the same time, and for the RFID device tocommunicate simultaneously in both modes. Control signals may also beused to temporarily or permanently disable operations in one or bothmodes.

FIG. 1 shows a simplified layout of an RFID device 10. The RFID device10 includes a chip or integrated circuit 12 and an antenna 14. Theantenna 14 may have any of a variety of well-known configurations, suchas that of a loop antenna, dipole antenna, or slot antenna. The antenna14 is operatively directly or indirectly electrically coupled tocontacts of the chip 12 in order to send and receive signals incommunication with another device, such as a reader or a detector. Thecommunication may be more passive, with the RFID device 10 drawing powerfrom an electric field, a magnetic field, or a propagatingelectromagnetic wave (or any combination thereof) produced by a readeror a detector, and using the power to alter or modulate the electricalfield. References elsewhere herein to use of an electric field should beunderstood as alternatively involving a magnetic field, a propagatingelectromagnetic wave, or any combination electric fields, magneticfields, and propagating electromagnetic waves. Alternatively, thecommunication may be active communication, with signals actuallybroadcast from the RFID device 10.

The chip 12 may be any of a variety integrated circuit devices used forcontrolling communication of the RFID device 10. Functions of the chip12 are carried out by circuitry of the chip, using a variety ofwell-known electronic structures. The chip 12 may be directly connectedto the antenna 14, or may alternatively be coupled to the antenna 14using an intervening structure such as an interposer or strap. Such aninterposer or strap may have conductive leads that facilitate electricalconnection between the chip 12 and the antenna 14. Such electricalconnection may be an electrical connection direct contact, characterizedby a low electrical resistance, or alternatively a reactive electricalconnection, where the contact is via an electric field, magnetic field,or combination.

The RFID device 10 may be embodied as a label or a tag, and may beattached or mechanically coupled to an object in any of a wide varietyof ways. The RFID device 10 may include a variety of other layersincluding adhesive layers, release layers, printable layers, and/orcoating layers.

Referring now to FIGS. 2 and 3, the RFID device 10 has an RFID mode ofoperation that is suitable for communication with an RFID reader ordetector 20. The RFID device 10 also has an EAS mode of operation thatis suitable for communication with an EAS detector 24 (FIG. 3). Thecircuitry of the chip 12 may control which mode the RFID device 10 isoperating in at any given time. The selection of RFID mode or EAS modemay be made automatically by the RFID device 10, based oncharacteristics of the incoming signals received by the RFID device 10,or on characteristics of UHF signals detected by the RFID device 10.Alternatively or in addition, the RFID device 10 may be configured toshift mode, and/or to deactivate communication in either mode, uponreceipt and processing or one or more specialized control signals. Asanother alternative, the RFID device 10 may be able to operate in bothmodes simultaneously.

The RFID device 10 operates differently in the RFID mode and the EASmode, to account for the different environments encountered in RFID andEAS communications, and the different requirements and desirablecharacteristics of RFID and EAS communications. For instance, EASenvironments involve situations where intervening objects, such aspeople, may be placed between the RFID devices and a reader/detector todetect such objects in an EAS application. UHF far field penetration isrelatively poor through wet dielectric objects such as people. The term“far field” is used in contrast to the term “near field,” which refersto a region closer to an antenna. Both terms describe the fields aroundan antenna (or any other electromagnetic radiation source). The boundarybetween the near field and the far field is often taken to be a distancefrom the antenna equal to N2rr, where A. is the wavelength of theradiation being emitted by the antenna, although it should be realizedthat sufficient energy is available to operate a RFID device designed tocouple via magnetic or electric field coupling at ranges much greaterthan this depending on the interrogator antenna design and power input.It is commonly understood that the region where powering via a primarilysingle field component, retaining the advantageous characteristics ofnear field coupling, is possible out to approximately 1 wavelength awayfrom the read system.

Accordingly, it is desirable for the RFID device 10 to have bettersensitivity in the EAS mode than in the RFID mode. From another point ofview, it is desirable for the RFID device 10, when in the EAS mode, tobe activated with less power than in the RFID mode. This can beaccomplished by having the RFID device 10 use less power when in the EASmode than when in RFID mode.

The frequency in the EAS mode may be within the UHF range given above,or may be at lower frequency out of the UHF range given above. Forexample, the frequency in the EAS mode may be as low as 100 MHz. Athigher frequency there is generally more available bandwidth. For thelower frequencies, generally available bandwidths are much smaller, so alow bandwidth protocol, such as 180180006-A can be used, which is a “tagtalks first” protocol that does not involve reader modulation, and hasthe additional advantage or requiring much simpler logic and no analoguereceive section in the chip, reducing power consumption and increasingrange.

FIG. 4 illustrates one way in which the RFID device 10 may have itsoperation modified in the EAS mode. The chip 12 has a number of digitalblocks 30 in its circuitry. The digital blocks 30 control variousfunctions of the RFID device, such as access to memory, reading andwriting of memory, receiving and processing commands, generating CRC's,security functions such as passwords and encryption, generating specificresponse messages, and handling a contention access protocol. Some ofthese functions are not necessary for use of the RFID device 10 in anEAS function. The EAS mode may involve the chip 12 shutting down certainof the digital blocks 30 that are necessary for communication in the EASmode. For example, the digital blocks 30 for keeping items in memory maynot be needed for the EAS function, since the response from the RFIDdevice 10 in EAS mode can be a single virtual bit when the device 10encounters an electric field (or the alternatives described elsewhereherein) from an EAS device detector or reader. The RFID device 10,whenever in the EAS mode, may respond by sending this single virtual bitwhenever it senses the presence of an EAS device detector. By shuttingdown some of the digital blocks 30, power consumption of the RFID device10 is reduced, the power requirement for activating the RFID device 10is thereby also reduced, and the sensitivity of the RFID device 10 isthus increased. It will be appreciated that a wide variety of digitalblocks can be shut off or temporarily disabled for the EAS mode. Forexample, in the 180180006-A protocol, the logic is a shift register withtaps to generate pseudo-random delays, which then simply clocks a shiftregister containing a code to the output modulator at intervals. Moresimply, the device can reflect a simple tone when it has sufficientpower, using a low modulation depth on the reflective modulator so itcan still receive sufficient energy—in fact, the modulation transistoritself, which is across the RF input, can be configured as a relativelylow frequency oscillator, so the only parts of the chip operating are arectifier and modulation transistor.

FIG. 5 illustrates another option of the changes for the EAS mode, inwhich the RFID device 10 does not store as much power in the EAS mode.The digital blocks 30 include a power storage block 34 that stores powerfor the RFID device 10 to perform a response to a situation. The powerstorage block 34 may include, for example, a charge pump/regulator witha capacitor or capacitors to store energy. For example the power storedin the power storage block 34 may be used to send a message along theantenna 14 or to reflect the incoming signal to modulate the electricfield (or alternatives to the electric field) in the vicinity of theRFID device 10. In passive RFID tags, communication back to the readersystem is commonly achieved using a modulated reflection, also commonlyreferred to as a modulated backscatter. In this technique the inputimpedance of the chip is changed by a data-carrying signal. In a simpleimplementation, the first impedance is that of the chip in the state itreceived power and commands from a reader system, and the secondimpedance is a lower impedance caused by a transistor across the chipantenna connection terminals being switched on. If we assume that theantenna impedance is a conjugate match to the chip impedance in itsfirst state, all the power received by the antenna will be absorbed bythe chip. When the modulator transistor is switched on, presenting asecond impedance, a portion of the power will now be reflected andre-radiated by the antenna towards the reader/interrogator. This can beconsidered as a form of reflective amplitude modulation, and creates adetectable signal in a properly designed reader system. In real worldtag designs, frequently the reflected signal is generated by acombination of amplitude and phase modulation, and the chip may havemore than two impedance states to enhance the modulationcharacteristics.

As noted in the previous paragraph, the signal from the RFID device 10may be a single virtual bit in the EAS mode. It will be appreciated thatthe power required to send a single virtual bit is much less than thatrequired to send a longer string of bits, such as often is done for RFIDcommunication, where transmission of particular device information maybe required. Thus the power required to operate in the EAS mode may besignificantly less than the power required to operate in RFID mode.Since less power is required for activation of the RFID device 10, thechip 12 may include instructions to respond in the EAS mode with lesspower stored in the power storage block 34 than would be necessary forRFID communication in the RFID mode. This means that in this embodimentthe RFID device 10 has greater sensitivity because it requires lesspower to be stored before it is activated to communicate. It will beappreciated that less power storage may be required for the EAS mode forother reasons than a shorter communication response.

The shorter response discussed above may involve sending only part ofthe normal communication message sent in the RFID mode. For example, inthe RFID mode the RFID device 10 may be configured for sending a fullinformation-carrying signal, carrying a potentially wide variety ofinformation about the RFID device 10, such as information individual tothe RFID device 10 and to the object that the RFID device 10 ismechanically coupled to. In EAS mode it may be sufficient to omit someor all of the individualized information. As one example, in the EASmode the RFID device 10 may be configured to send only a partialresponse, such as a preamble section of a normal communication sent inthe RFID mode.

The RFID device 10 may also make a reduced modulation response in theEAS mode, with the modulation reduced relative to the RFID mode. Thismay be done in addition to or alternatively to the above changes for theEAS mode. As the chip 12 makes a reflected response it sends forth acontinuous sequence of 1 and 0 bits at a known frequency. In the EASmode the chip 12 may be configured to reflect an incoming signal withless of an impedance change than in the RFID mode. Since the chip 12 isreflecting less it can rectify power during the response period. Thisenhances the sensitivity of the RFID device 10 when it is communicatingin the EAS mode. The weaker response in the EAS mode might be a problemfor RFID communication, as RFID communication ordinarily requiresbroadband communication. However, for the EAS mode it may be acceptableto communicate in a narrowband tone. An EAS reader may be configured tohave its effective bandwidth reduced. This reduces the noise floor forcommunication between the RFID device 10 (in EAS mode) and the EASreader/receiver. This enables detection of weaker signals (increasedsensitivity).

The chip 12 impedance may also be changed for the EAS mode. In RFIDcommunication it is desirable that the chip and the antenna of a devicenot be an exact conjugate match, in order to achieve optimal bandwidthabout a desired frequency. Such bandwidth may be desirable in RFIDcommunication, since RFID readers/detectors may need to communicate withmultiple RFID devices at the same time. This need to have the capabilityto communicate with multiple RFID devices simultaneously leads to adesirability for some significant bandwidth in the RFID communicationsystem. Such systems may require a substantially stable frequency duringcommunication, such that fast frequency hopping is not desirable. Anarrower bandwidth may be acceptable for the EAS mode, since EAS systemsoften do not require any sort of complex information exchange betweendevices and readers, so in that instance frequency hopping may beacceptable. In addition, the short communications of EAS systems, andthe requirements of such systems, lessen or avoid altogether the need ofa capability of communicating with multiple devices simultaneously. Theimpedance of the chip 12 may be alterable in any of a variety of ways,which may be internally switchable within the chip 12. One method ofaltering the impedance is by changing the load presented to therectifier circuits, as the input impedance is partially dependant on thecurrent flow through the rectifier. Other methods involve the use ofnon-volatile memory cells which provide bias to sections of the circuit,or having a series of transistors controlled by memory cells connectingcapacitors formed on the chip across the input.

Referring now in addition to FIG. 6, the chip 12 may have a first set ofcontacts (first port) 42 for connection to a first antenna 44, and asecond set of contacts (second port) 46 for connection to a secondantenna 48. The first contacts 42 and the first antenna 44 may be usedfor communication in the RFID mode, and the second contacts 46 and thesecond antenna 48 may be used for communication in the EAS mode. Thecontacts/antenna combinations may be optimized for the individualcharacteristics of their respective modes. The first contacts 42 mayhave different impedance than the second contacts 46. The first contacts42 may be configured to work well with far field antennas and givebroadband frequency responses, for communication in the RFID mode. Thismay be accomplished by keeping the ratio of the real and reactive partsof the first contacts 42 relatively low. This is the equivalent of theconcept of Q in low frequency circuits. The term Q in this contextrelates to the behavior of a resonant tuned circuit, comprising aninductance, presented by the antenna, a capacitance presented by thechip and a resistance presented by the chip and any other energy lossmechanisms in the structure, such as dielectric loss in materials. Onedefinition of Q is the ratio of the total energy stored to the energylost per cycle. Energy is stored in the inductor and capacitor (at zerovoltage all the energy is in a magnetic field in the inductor, at zerocurrent the energy is stored in the capacitor as a voltage) and theresistance dissipates energy. Q is calculated for a parallel model, themost appropriate for an RFID chip input, as the ratio of resistance toreactance. For a resonant circuit XL and X care equal, but in practicalterms there may be a high resistance and a high capacitance/lowinductance. A high Q circuit can be useful for the input of an RFID chipis that it can effectively multiply the AC voltage at the chip input,where the AC voltage represents the energy stored, which can be higherthan the energy delivered per cycle by the radio frequency source. Thisis important as two factors determine the ability of an RFID chip tooperate: one is getting enough power, and the other is getting enough RFvoltage at the input to allow the rectifiers to function. Rectifiers,either diodes or synchronous types using transistors, tend to have athreshold voltage where forward conduction starts. For diodes, this mayrange from approximately 0.3V to 0.7V for silicon devices, depending ondoping levels. This threshold can be reduced, but at a point, thereverse leakage current of the diode when reverse biased becomes large,and effectively the efficiency of the conversion of RF energy to DCvoltage becomes unusable. So making a chip with very low powerconsumption will not always ensure that it will operate at low RF powerinputs, as the voltage has to be large enough. By having a highresistance input, and using resonance, higher voltages can be achieved,although the chip cannot draw higher power than is delivered per cycleto the circuit, or the voltage drops. The negative impact of higher Q isthat the bandwidth of operation is greatly reduced—a typical measure isthe 3 dB bandwidth LiF=f/Q. This narrow bandwidth may present a problemfor normal RFID operations, where consistent performance over a band isdesired. However, for an EAS function, as there is no time consumingcommunication or protocol taking place, so it is possible to rapidlyscan through a frequency band to find the operating frequency of a tagin EAS mode, overcoming the problem caused by both the narrow bandwidthand de-tuning effects from attempts to defeat the EAS function. Thehigher sensitivity achievable in EAS mode may also allow a lower powertransmission to be used for detection, and, depending on regulatorylimits, a broader bandwidth, again improving the chances of catching adeliberately off-tuned tag device. The fast frequency hopping spread thereader energy effectively over a band so also reduces the impact onother systems. The second contacts 46 thus may have a higherreal-to-reactive ratio (high Q), suitable for use in the EAS mode. Forexample a chip may have a real part of 10000 ohms and a capacitance of 2pF (−87 ohms reactive at 915 MHz). This gives a theoretical maximumunloaded Q of −115, but the chip adsorbing energy from the circuit, willreduce the effective loaded Q to a lower value. The characteristics ofthe second contacts 46 may generate a higher voltage for any given inputpower, which results in greater sensitivity, at least in a voltagelimited situation. Such characteristics are more suited to near-fieldreading and use in the EAS mode, but would be less suitable for regularRFID communication.

It will be appreciated that many possible ways of selecting a mode ofoperation. For instance the device may be configured to only reply inEAS mode when a set of conditions are met. For chips having multipleinputs (contacts or ports), such conditions may include on which input acommand (if any) is received. For example, if a chip has two inputs, onefor EAS communication and one for RFID communication, the system may beset to respond in EAS mode if a communication, such as an EAS-typecommunication, is received on both inputs. If the same communication isreceived on only an input coupled to an RFID antenna, the device may beconfigured to not respond at all. This enables the possibility ofdeactivating the EAS function by physically breaking the antenna usedfor EAS communication. Such an alteration would leave the device stillable to function as an RFID device. It will be appreciated that manyother variations are possible.

An alternative configuration would be to have a single antenna coupledto both first set of contacts 42 and 46. The sets of contacts 42 and 46may be coupled to different respective points on the single antenna,representing different matching conditions. As another alternative, thesets of contacts may be connected to different elements in the sameantenna, with the contact sets sharing one a contact.

As an alternative, shown in FIG. 7, the second contacts or port 46 couldbe configured with a very high input capacitance (e.g., 2-20 pF) and ahigh real part of the impedance (e.g., between 5000 and 20000 ohms).This allows a conductor loop 50 to be placed in parallel with the port46, and to be resonant at UHF frequencies. The loop 50 allows a verylarge Q. The loop 50 encloses an area 52. This enclosed area 52 enhancesthe new magnetic field sensitivity for the antenna 48.

The RFID device 10 described in the various embodiments above may be aUHF RFID device. UHF antennas and readers are small compared to thereaders and detection devices commonly employed for detecting magneticEAS devices. This allows EAS detection to be performed unobtrusively,such as by mounting in or on a ceiling or floor. This removes obstaclesat a store's exit.

In addition it will be appreciated that a cost saving is involved inintegrating the RFID and EAS functions in a single RFID device, withoutthe need for additional structural components to perform the EASfunction. This results in increased functionality with little or noincrease in the cost of the RFID device.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (components, assemblies,devices, compositions, etc.), the terms (including a reference to a“means”) used to describe such elements are intended to correspond,unless otherwise indicated, to any element which performs the specifiedfunction of the described element (i.e., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary embodiment or embodiments of the invention. In addition, whilea particular feature of the invention may have been described above withrespect to only one or more of several illustrated embodiments, suchfeature may be combined with one or more other features of the otherembodiments, as may be desired and advantageous for any given orparticular application.

1. A radio frequency identification (RFID) tag, comprising: a chip; andan antenna operatively coupled to the chip; wherein the chip includingcircuitry for operation between a first mode and a second mode; andwherein each of the first and second modes operate at a differentsensitivity.
 2. The RFID tag of claim 1, wherein the chip deactivateseither the first or second mode on receipt of a signal.
 3. The RFID tagof claim 1, wherein one of the first or second mode is an EAS mode andthe a further mode is a RFID mode.
 4. The RFID tag of claim 3, whereinthe chip uses less power in the EAS mode than in the RFID mode.
 5. TheRFID tag of claim 3, wherein the circuitry includes circuitry forswitching off digital blocks of the circuitry for the EAS mode.
 6. TheRFID tag of claim 1, wherein the first mode is a relatively lowsensitivity RFID mode and the second mode is a relatively highsensitivity EAS mode.
 7. The RFID of claim 1, wherein the enteringincludes reducing power storage required in a chip of the RFID devicebefore communicating with the EAS reader/detector.
 8. A radio frequencyidentification (RFID) tag, comprising: a chip; and at least one antennacoupled to the chip; wherein the chip includes circuitry for operatingat a normal mode and at least a second mode, and wherein the chipselectively operates between the normal mode and the second mode; andwherein the chip deactivates one of the normal mode and second mode onreceipt of a signal.
 9. The RFID tag of claim 8, wherein the RFID deviceis a UHF RFID device.
 10. The RFID tag of claim 8, wherein the at leastone antenna is coupled to contacts of the chip.
 11. The RFID tag ofclaim 8, wherein the second mode has an improved sensitivity in thenormal mode.
 12. The RFID tag of claim 8, wherein the normal mode isused for RFID communication.
 13. The RFID tag of claim 12, wherein thesecond mode has an improved sensitivity and is used for communicationwith an EAS reader/detector.
 14. The RFID tag of claim 13, wherein thenormal mode requires more power to operate than the second mode.
 15. TheRFID tag of claim 13, wherein the RFID device has its operation modifiedin the second mode.
 16. The RFID tag of claim 13, wherein the devicedoes not store as much power in the second mode.
 17. The RFID tag ofclaim 8, wherein the chip has a number of digital blocks in itscircuitry.
 18. The RFID tag of claim 17, wherein the digital blocksinclude a power storage block.
 19. The RFID tag of claim 18, wherein thepower storage block includes a charge/pump regulator with at least onecapacitor.
 20. A radio frequency identification (RFID) tag, comprising achip having at least two inputs; an EAS antenna coupled to the chip anda RFID antenna coupled to the chip; the RFID tag can receive signals inone of two modes; and wherein a signal received by the RFID antennadeactivates the EAS antenna.